TOEFL Reading: ETS-TOEFL阅读机经 - 5HWS66ZAS559633EL$

Which of the following most accurately reflects the statement discussed in paragraph 5, on efforts to cultivate plants and animals? A. The efforts often failed because hunter-gatherers had limited access to new information about plants and animals. B. The efforts were begun out of a desire to produce goods for trade rather than to increase their growers' food supplies. C. The efforts were sometimes abandoned so hunter-gatherers could become involved in the more profitable activity of trading. D. The efforts were not profitable until people began trading food that they had raised for other goods.